CN113088611B - Pure oxygen two-stage preheating reduction iron-making process - Google Patents
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
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- C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces
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- C21B13/0046—Making spongy iron or liquid steel, by direct processes making metallised agglomerates or iron oxide
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/006—Starting from ores containing non ferrous metallic oxides
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22B1/16—Sintering; Agglomerating
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- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22B1/00—Preliminary treatment of ores or scrap
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Abstract
The invention relates to a pure oxygen two-stage preheating reduction ironmaking process, which is matched with a pure oxygen two-stage preheating reduction ironmaking furnace, and comprises the following process steps of pretreating iron ore or iron powder ore/fly ash, conveying the pretreated iron ore or iron powder ore/fly ash to an ore bin, and spraying the pretreated iron ore or iron powder ore/fly ash into a preheating section of the ironmaking furnace through a spray gun; the ore powder is heated to be melted and flows to a reduction section after being partially pyrolyzed/reduced; reducing the ore powder into ferrous oxide in a reduction section, and dropping the ferrous oxide into a metal molten pool; coal powder is sprayed into a furnace hearth section molten pool, and part of the coal powder is dissolved into the molten pool and reacts with ferrous oxide for reduction reaction to generate CO and molten iron; the CO and coal volatile matter rises to drive the high-temperature liquid metal and slag to form a Yongquan; rising gas and O introduced into reduction zone 2 Burning to transfer heat to liquid metal and slag drops brought up by the Yongquan, and dropping the liquid drops to transfer heat to a molten pool and stir the molten pool and ensure that a reduction reaction is carried out; the flue gas discharged from the furnace is dedusted by a gravity deduster, and the flue gas waste heat is used for preheating the mineral powder and the coal powder. The invention has simple process flow and is environment-friendly.
Description
Technical Field
The invention relates to a smelting reduction iron-making process, in particular to a pure oxygen two-section type preheating reduction iron-making process, belonging to the technical field of non-blast furnace iron-making.
Background
Blast furnace ironmaking techniques and process equipment using coke have been over 400 years old and are the most mature ironmaking process to date. However, the blast furnace ironmaking technology still has obvious defects, which are mainly reflected in four aspects: high-proportion coking coal is used in the ingredients; environmental emissions problems associated with coking and sintering; the fine ore can not be directly used for charging; and the dephosphorization is impossible. Therefore, research on new iron-making technologies is actively carried out at home and abroad, and some successful cases are achieved, such as smelting technologies of rotary kilns, tunnel kilns, rotary hearth furnace methods, Corex processes, Finex technologies, HIsmelt technologies and the like of carbon-containing pellets.
The smelting temperature of the rotary kiln method is about 1100-1200 ℃, the smelting temperature is low, the yield of Zn and Pb is low, the metallization rate of products is low, and the improvement of the smelting temperature can improve the yield of Zn and Pb and the metallization rate of products, but the problems mainly exist are that the kiln is looped, the operation rate is seriously influenced, and the reason is also the main reason for restricting the development of the rotary kiln.
As a comprehensive treatment process of metallurgical dust, the rotary hearth furnace method has the characteristics of high reduction reaction speed and high resource utilization efficiency, and provides a new way for efficiently utilizing the solid wastes of the iron and steel enterprises. The rotary hearth furnace process has built a plurality of production lines at home at present, and production practices show that the technology for treating zinc-containing metallurgical dust and sludge by the rotary hearth furnace process is mature, but the process has the disadvantages of high fuel consumption and high production cost, and the utilization approach is limited because the metallized pellets belong to semi-finished products.
The Corex process developed by KORF company of germany and austria in the austria combines two mature processes of shaft furnace and coal gasification, performs pre-reduction of iron-containing materials in the shaft furnace, and performs final reduction and coal gasification by using a coal fluidized bed as a smelting container. Corex is the earliest commercial and industrial smelting reduction iron-making process, but the process has strict requirements on raw fuel, complex equipment and short service life compared with a high furnace, and is not beneficial to popularization of the process.
Commercial Finex technology developed by korean POSCO corporation based on Corex process has also achieved industrial production, but the Finex technology has huge investment cost, higher production cost than conventional blast furnaces, and still relies on coke, with high requirements for raw materials.
The HIsmelt technology which is dominated by the australian force company is a technology which is most likely to realize industrialization at present, and the basic process route is similar to the Finex technology, but the HIsmelt technology is more attractive than the Finex technology, and has better application prospect in the aspect of smelting ore species, such as process parameters obtained by directly smelting high phosphorus ore and the like, than the Finex technology.
The main equipment shell of a smelting reduction furnace (SRV) used by the HIsmelt technology consists of an upper water-cooled furnace shell and a furnace hearth with a built refractory material at the lower part, coal and part of mineral powder are sprayed into a molten pool at high speed by a downward inclined water-cooled spray gun, and the sprayed mineral powder is in contact with carbon-rich molten iron and then is subjected to reduction smelting; blowing 1200 ℃ oxygen-enriched hot air from a top spray gun, mixing the oxygen-enriched hot air with coal gas (main component CO) at the upper part of a molten pool, and burning the mixture in an upper oxidation zone to maintain the heat required by the heat balance in the furnace. However, this process also has some disadvantages: the furnace gas discharged from the furnace top is low-calorific-value coal gas, the temperature is as high as about 1400 ℃, the heat energy utilization rate is low, the advantages of process energy consumption and production cost are not obvious, the corrosion and damage of refractory materials are serious, and the time for really popularizing and applying in mass production is relatively short.
Disclosure of Invention
The invention aims to solve the problems of high emission, high pollution and high energy consumption of the existing iron-making process, and provides a pure oxygen two-stage preheating reduction iron-making process which is simple in process flow, convenient to operate, capable of ensuring production of high-quality molten iron, capable of treating iron-containing dust, capable of fully utilizing heat of recovered furnace gas to preheat mineral powder and coal powder, comprehensively recovering valuable metals such as Zn, Pb and the like in raw materials, achieving energy-saving and consumption-reducing effects of kiln operation and meeting the requirements of national standard and enterprise standard on low pollutant emission.
In order to realize the purpose, the invention adopts the technical scheme that: the pure oxygen two-stage preheating reduction iron-making process includes pre-treating material, crushing iron ore and flux in a crusher to 6mm below size, or crushing iron powder, dedusting ash or mixture of iron-containing dust and mud, adding water and adhesive, pelletizing, stoving, crushing in a crusher to 6mm below size and drying; meanwhile, the coal is also dried and crushed into coal powder; the mineral powder and the coal powder are sprayed into the furnace body by taking flue gas as a power medium; the process is matched with a pure oxygen two-stage preheating reduction iron-making furnace for use; the process specifically comprises the following steps:
the first step is as follows: conveying the dried mineral powder to a mineral bin by a high-temperature bucket elevator chain conveyor, and spraying the mineral powder into the upper section of the preheating section of the iron-making furnace body by a plurality of cyclone mineral powder spray guns through a screw feeder;
simultaneously connecting oxygen pipelines of an oxygen supply station connected with the furnace body, wherein one path of oxygen is connected with a plurality of tertiary combustion oxygen spray guns to enter the middle section of the preheating section, one path of oxygen is connected with a plurality of secondary combustion oxygen spray guns to enter the lower section of the preheating section, and the other path of oxygen is connected with a plurality of oxygen lances to enter the reduction section;
the dried and crushed coal powder is synchronously sprayed into the surface of the metal molten pool of the hearth section through a plurality of coal guns arranged on the reduction section;
the second step is that: the ore powder is heated to 1000-1400 ℃ in the preheating section of the furnace body by oxygen sprayed by the secondary combustion oxygen spray gun and the tertiary combustion oxygen spray gun, heat released by combustion of high-temperature furnace gas from the reduction section and physical heat of the high-temperature furnace gas, and the ore powder flows downwards to the reduction section after being melted and partially pyrolyzed/reduced; the mineral powder is rapidly reduced into ferrous oxide on the upper part of the reduction section and then drops into a metal molten pool;
the third step: volatile matters in the coal dust sprayed into the surface of the metal molten pool of the hearth section enter the furnace gas, and the residual carbon particles are dissolved in the metal molten pool and subjected to reduction reaction with reduced ferrous oxide in the mineral powder to generate CO and molten iron; the CO, furnace gas and coal volatile matter rise and drive high-temperature liquid metal and slag to form a Yongquan; CO, coal volatile matter and O introduced from oxygen lance at the upper part of reduction section 2 Carrying out combustion reaction, transferring the generated heat to liquid metal and slag drops brought by the phenomenon of 'spring gushing', transferring the heat to a metal molten pool through drop falling, strongly stirring the metal molten pool and ensuring the reduction reaction;
the fourth step: molten iron smelted by the reduction reaction flows into a molten iron tank from a tap hole arranged at the lower part of the furnace body, and generated slag is discharged from a slag hole; the furnace gas temperature of the reduction section is 1400-1580 ℃, the furnace gas is preheated when rising to the preheating section, and the combustible is completely combusted; and (3) discharging the flue gas generated by the reduction reaction through a smoke discharge section at the upper part of the furnace body, wherein the temperature is 500-600 ℃, the flue gas is dedusted by a gravity deduster and then used for preheating and drying the powdered ore and the pulverized coal, the temperature of the flue gas is reduced to 100-150 ℃, the flue gas is dedusted by a cyclone and a cloth bag, one part of the purified flue gas is pressurized by a pressurizer to be used as a power medium for blowing the pulverized coal or the powdered ore, and the other part of the flue gas is directly discharged.
The furnace body of the pure oxygen two-section type preheating reduction ironmaking furnace is provided with a smoke exhaust section, a preheating section, a reduction section and a furnace hearth section; a plurality of cyclone type mineral powder spray guns, a tertiary combustion oxygen spray gun and a secondary combustion oxygen spray gun are sequentially arranged on the upper section, the middle section and the lower section of the wall of the preheating section furnace and are all arranged at an angle tangent to a tangential circle in the furnace; an oxygen lance is arranged on the upper section of the reduction section, a coal lance is arranged on the lower section of the reduction section, and a nozzle of the oxygen lance and a nozzle of the coal lance point to a metal melting bath on the lower furnace hearth section; the inner side of the furnace hearth section is provided with a ceramic cup used as a metal melting bath, and the side surface of the furnace hearth section is provided with an iron outlet and a slag outlet.
The cyclone type mineral powder spray gun, the tertiary combustion oxygen spray gun and the secondary combustion oxygen spray gun all enter the preheating section at an angle tangent to a tangential circle, the sprayed mineral powder and oxygen form a rotating fluid in the preheating section, the rotating fluid enhances the mixing of furnace gas, oxygen and mineral powder, so that all combustible materials are burnt out, and the mineral powder is ensured to be intensively preheated in the process that the mineral powder falls to the reduction section in a manner of rotating along the furnace wall in the preheating section.
In the first step, 1-8 cyclone mineral powder spray guns are arranged in the preheating section, 1-4 tertiary combustion oxygen spray guns are arranged, and 1-4 secondary combustion oxygen spray guns are arranged; 2-9 coal guns are arranged at the reduction section, and 1-12 oxygen guns are arranged at the reduction section.
In the first step, the speed of spraying the mineral powder into the preheating section of the furnace body of the iron-making furnace is controlled to be 20-40 m/s; controlling the speed of oxygen injection to be 22-60 m/s; the speed of the pulverized coal sprayed into the surface of the metal molten pool is 20-45 m/s.
The ore powder in the first step is sprayed into the preheating section, the temperature of furnace gas rises from the reduction section to the lower section of the preheating section to exchange heat with the ore powder, oxygen for secondary combustion added from the secondary combustion oxygen spray gun is combusted with the furnace gas to increase the furnace temperature, and the heat for preheating the ore powder in the lower section of the preheating section is maintained; the middle section furnace gas in the preheating section is combusted with oxygen supplemented by a tertiary combustion oxygen spray gun to ensure that combustible substances in the furnace gas are fullBurning out, improving fuel utilization rate and reducing CO 2 And (5) discharging.
The ore powder in the second step flows down to the reduction section after being melted and partially pyrolyzed/reduced in the preheating section, and the degree of pre-reduction of the ore powder is 15-20%.
Compared with the prior art, the pure oxygen two-stage preheating reduction iron-making process has the advantages that:
the pure oxygen two-stage preheating reduction iron making process has the advantages that the energy consumption is lower than that of a blast furnace, the process is high in adaptability to raw materials and fuels, iron ore powder and non-coking coal powder can be directly used for smelting, dependence on coke resources is completely eliminated, and the process is particularly suitable for treating high phosphate ore and vanadium-titanium magnetite. The process completely omits the procedures of coking, sintering, pelletizing and the like, is low-carbon and clean, and obviously reduces the pollutant emission. Compared with the blast furnace process, the process of the invention omits the step of raw material treatment, SO x Emission reduction of 90%, NO x The emission is reduced by 40 percent, and CO 2 The emission is reduced by more than 20 percent.
The iron-making process can directly use low-grade iron ores and steel plant circulating wastes of factories, can also treat iron dust such as iron-containing powder high in Zn and Pb, can mix and spray the iron-containing powder and mineral powder, can achieve the iron recovery rate of 95 percent, and can fully utilize valuable metal resources such as zinc, lead and the like contained in the dust.
The process adopts flue gas instead of N which is usually used 2 As the blowing medium and the flue gas cooled and purified by tapping are used as the power medium, the generation amount of thermal NOx products can be reduced, and the CO in the flue gas can be improved 2 The concentration is more than or equal to 90 percent, and the reduction of CO compared with the prior blast furnace process can be realized by combining the carbon capture and storage technology 2 Discharge 80% of the target.
The method has the characteristics of simple process flow, convenience in operation, safety and reliability in operation, high product quality, environment friendliness and the like. The whole production operation process of the iron-making process can fully utilize the heat of the furnace gas, achieve the purposes of saving energy, reducing consumption, meeting the requirements of national standard and enterprise standard on low pollutant emission, realizing low-carbon green iron-making and meeting the requirements of clean steel production; the iron-making process has high popularization value.
Drawings
FIG. 1 is a schematic block diagram of a pure oxygen two-stage preheating reduction ironmaking process.
FIG. 2 is a schematic structural view of a pure oxygen two-stage preheating reduction iron-making furnace used in cooperation with the process.
In the above figures: 1-a smoke exhaust section; 2-a preheating section; 3-a reduction section; 4-hearth section; 5-a coal gun; 6-tapping hole; 7-a cooling water pipe; 8-graphite carbon brick; 9-carbon ramming mass; 10-plate type cooling wall; 11-a ceramic cup; 12-a slag outlet; 13-inlaying brick cooling walls; 14-oxygen lance; 15-a post combustion oxygen lance; 16-three-time combustion oxygen spray gun; 17-cyclone type mineral powder spray gun; 18-a steel shell; 19-a stave; 20-refractory bricks; 21-pressing in refractory material; 41-molten metal bath.
Detailed Description
The pure oxygen two-stage preheating reduction ironmaking process of the invention is further described in detail with reference to the accompanying drawings and specific examples, which are only used for illustrating the process of the invention, but the implementation of the invention is not limited thereto.
Example 1: the invention provides a pure oxygen two-stage preheating reduction ironmaking process, which is shown in figure 1, and comprises the following steps of: the ore raw material in the embodiment is iron-rich lump ore, the iron-rich lump ore and fluxes such as limestone are directly crushed into ore powder with the diameter less than or equal to 6mm by a crusher, and the ore powder is dried and dried by recovered flue gas in a drum dryer and heated to about 250 ℃; meanwhile, the coal is also crushed into coal powder by a drying hammer crusher and is conveyed to a screw feeder by a chain conveyor; the mineral powder and the coal powder are respectively sprayed into the furnace body by taking flue gas purified after cyclone dust removal and cloth bag dust removal as a power medium; the process of the invention is used in combination with a pure oxygen two-stage preheating reduction ironmaking furnace, see figure 2. The process specifically comprises the following steps:
the first step is as follows: conveying the dried mineral powder to a mineral bin by a high-temperature bucket elevator chain conveyor, and spraying the mineral powder into a preheating section 2 of the iron-making furnace body by a screw feeder through 1 cyclone mineral powder spray gun 17; spraying the mineral powder at a speed of 20 m/s;
simultaneously, an oxygen pipeline of an oxygen supply station connected with the furnace body is communicated, wherein one path of oxygen is connected with 1 tertiary combustion oxygen spray gun 16 and enters the middle section of the preheating section, one path of oxygen is connected with 1 secondary combustion oxygen spray gun 15 and enters the lower section of the preheating section, and the other path of oxygen is connected with 1 oxygen lance 14 and enters the reduction section 3; controlling the oxygen spraying speed to be 22 m/s;
the dried and crushed coal powder is synchronously sprayed into the surface of a metal melting pool 41 of a hearth section 4 through 2 coal guns 5 arranged on a furnace body by taking flue gas as a power medium, and the spraying speed is 20 m/s.
The second step: the mineral powder is heated to near 1400 ℃ in the preheating section 2 of the furnace body by oxygen sprayed by the secondary combustion oxygen spray gun 15 and the tertiary combustion oxygen spray gun 16 and high-temperature furnace gas from the reduction section, and the mineral powder flows downwards to the reduction section 3 after being melted and partially pyrolyzed/reduced; the ore fines are rapidly reduced to ferrous oxide at the upper portion of the reduction stage and then dropped into the molten metal bath.
The third step: volatile matters in the coal dust sprayed on the surface of the metal molten pool 41 of the hearth section 4 enter furnace gas, and the remaining carbon particles are dissolved in the metal molten pool and undergo reduction reaction with ferrous oxide in the mineral powder to generate CO and molten iron; CO, furnace gas and coal volatile matter rise and drive high-temperature liquid metal and slag to form a Yongquan; CO, coal volatile matter and O introduced from the upper part of the reduction section through an oxygen lance 14 2 The combustion reaction is carried out, the generated heat is transferred to liquid metal and slag drops brought by the phenomenon of Yongquan, the heat is transferred to a metal molten pool through the falling back of the liquid drops, the metal molten pool is intensively stirred, and the reduction reaction is ensured to be carried out.
The fourth step: molten iron smelted by the reduction reaction is discharged from a tap hole 6 arranged at the lower part of the furnace body and flows into a molten iron tank, and generated slag is discharged from a slag hole 12; the temperature of furnace gas in the reduction section is about 1450 ℃, mineral powder is preheated when the temperature rises to the preheating section, combustible materials are completely combusted, the flue gas is discharged through a smoke discharging section 1 at the upper part of the furnace body, dust is removed by a gravity dust remover, the temperature of the flue gas is about 500 ℃, on one hand, valuable metal elements in the flue gas are recovered, on the other hand, the flue gas is used for re-preheating the mineral powder and drying the coal powder, the temperature of the flue gas is reduced to 120 ℃, then, the flue gas is subjected to cyclone dust removal and cloth bag dust removal, one part of the purified flue gas is pressurized by a pressurizer to be used as a power medium for blowing the coal powder or the mineral powder, and the other part of the flue gas is directly discharged.
The pure oxygen two-stage preheating reduction ironmaking process is implemented on a furnace body of a pure oxygen two-stage preheating reduction ironmaking furnace, and is shown in figure 2. The ironmaking furnace of the embodiment is a small ironmaking furnace, and is provided with a smoke discharging section 1, a preheating section 2, a reducing section 3 and a furnace hearth section 4; the upper section, the middle section and the lower section of the preheating section furnace wall are sequentially provided with 1 cyclone type mineral powder spray gun 17, a tertiary combustion oxygen spray gun 16 and a secondary combustion oxygen spray gun 15; the upper section of the reduction section is provided with 1 oxygen lance 14, the lower section is provided with 2 coal lances 5, and the oxygen lance and the coal lance spout point to the metal molten pool 41 of the furnace hearth section at the lower part; the furnace hearth section is provided with a ceramic cup 11 used as a metal melting bath, and two side surfaces of the furnace hearth section are respectively provided with 1 iron outlet 6 and 1 slag outlet 12. The preheating section furnace body is sequentially provided with refractory bricks 20, a cooling wall 19 and a steel shell 18 from the inner wall to the outer wall, and refractory materials 21 are filled and pressed in a gap between the cooling wall and the steel shell; the brick-inlaid cooling wall 13, the pressed refractory material 21 and the steel shell 18 are sequentially arranged on the wall of the reduction section furnace from the inner wall to the outer wall; the furnace hearth section is provided with a cooling water pipe 7, a graphite carbon brick 8, a carbon ramming material 9, a plate-type cooling wall 10, a ceramic cup 11 and a steel shell 18, and a furnace body of the furnace hearth section is also filled and pressed with a refractory material 21 in a gap between the steel shell 18 and the plate-type cooling wall 10; the ceramic cup is arranged on the inner side of the graphite carbon brick 8 masonry, the cooling water pipe is arranged at the bottom of the graphite carbon brick, the slag outlet and the tap hole are arranged at the hearth section, and the tap hole leans against the bottom side of the furnace.
According to the pure oxygen two-stage preheating reduction iron-making process, the temperature of the hearth section is 1370-1500 ℃; the temperature of furnace gas in the reduction section is 1400-1580 ℃; the temperature of furnace gas in the preheating section is 600-1420 ℃; the temperature of the flue gas at the outlet of the smoke discharging section is about 500-600 ℃, and CO in the components of the flue gas is 2 The concentration of (A) is more than or equal to 90 percent.
Example 2: the invention provides a pure oxygen two-stage preheating reduction ironmaking process, the structure and the ironmaking process of an ironmaking furnace are basically the same as those of the ironmaking process in the embodiment 1, and the difference is as follows:
the ironmaking furnace used in this embodiment is a medium-sized pure oxygen two-stage preheating reduction ironmaking furnace; 6 cyclone mineral powder spray guns 17 are arranged at the preheating section of the furnace body, 3 tertiary combustion oxygen spray guns 16 are arranged, and 3 secondary combustion oxygen spray guns are arranged; installing 6 oxygen guns and 6 coal guns on the reduction section; the number of the slag outlets and the iron outlets arranged on the hearth section is 2.
The ore raw material is high-phosphorus iron ore, the ore powder is heated to 1400 ℃ by physical heat and combustion chemical heat of high-temperature furnace gas from the reduction section in the preheating section, and the ore powder flows down to the reduction section after melting and partial pyrolysis/reduction; the speed of spraying the high-phosphorus iron ore powder into the preheating section is controlled to be 40 m/s; controlling the speed of the injected oxygen at 45 m/s; the velocity of the pulverized coal injected into the molten metal bath was 40 m/s.
Example 3: the invention provides a pure oxygen two-stage preheating reduction ironmaking process, the structure and the ironmaking process of an ironmaking furnace are basically the same as those of the ironmaking process in the embodiment 1, and the difference is as follows:
the ironmaking furnace used in this embodiment is a large-scale pure oxygen two-stage preheating reduction ironmaking furnace; mounting cyclone mineral powder spray guns in two layers at a preheating section of the furnace body, wherein 4 spray guns are respectively mounted on each layer, and 8 spray guns are mounted on each layer; 4 installed tertiary combustion oxygen spray guns and 4 installed secondary combustion oxygen spray guns; installing 12 oxygen guns and 9 coal guns on the reduction section; the number of the slag outlets and the iron outlets arranged on the hearth section is 2.
The ore raw material is mixed ore, and comprises the following components in percentage by mass: the method comprises the steps of containing 60% of oxidized ore and 40% of electric furnace dust, directly crushing the oxidized ore to be less than 6mm, adding water into the electric furnace dust, mixing, pressing balls, drying, and then crushing to be less than 6 mm;
the speed of spraying the mixed mineral powder into the preheating section is controlled at 30 m/s; controlling the speed of the injected oxygen at 60 m/s; the speed of the pulverized coal sprayed into the surface of the metal molten pool at the hearth section is 45 m/s;
the temperature of the discharged flue gas is about 600 ℃, and the discharged flue gas is sequentially used for preheating ores and drying coal powder after Zn is recovered by a gravity dust collector, and the temperature of the flue gas is reduced to about 100 ℃.
The iron-making process has the characteristics of strong adaptability of raw materials and fuels, simple process flow, easy operation, high product quality, environmental friendliness and the like, can directly use iron ore powder and non-coking coal powder for smelting, completely gets rid of the dependence on coke resources, and has higher popularization value.
Claims (2)
1. A pure oxygen two-stage preheating reduction ironmaking process comprises the steps of pretreating raw materials, crushing iron ore and a fusing agent by using a crusher until the granularity is less than or equal to 6mm, or crushing iron powder ore, dedusting ash or a mixture containing iron dust and mud by using a crusher after adding water and a bonding agent, pressing balls and drying until the granularity is less than or equal to 6mm, and drying; meanwhile, the coal is also dried and crushed into coal powder; it is characterized in that the process is matched with a pure oxygen two-stage preheating reduction iron-making furnace for use; the process specifically comprises the following steps:
the first step is as follows: conveying the dried mineral powder to an ore bin by a high-temperature bucket elevator chain conveyor, and spraying the mineral powder into the upper section of the preheating section of the furnace body of the iron-making furnace by a screw feeder through a plurality of cyclone mineral powder spray guns;
simultaneously connecting oxygen pipelines of an oxygen supply station connected with the furnace body, wherein one path of oxygen is connected with a plurality of tertiary combustion oxygen spray guns to enter the middle section of the preheating section, one path of oxygen is connected with a plurality of secondary combustion oxygen spray guns to enter the lower section of the preheating section, and the other path of oxygen is connected with a plurality of oxygen lances to enter the reduction section;
the dried and crushed coal powder is synchronously sprayed into the surface of the metal molten pool of the hearth section through a plurality of coal guns arranged on the reduction section;
the mineral powder and the coal powder are sprayed into the furnace body by taking flue gas as a power medium; the speed of spraying the mineral powder into the preheating section of the furnace body of the iron-making furnace is controlled to be 20-40 m/s; the speed of spraying the coal powder into the surface of the metal molten pool is 20-45 m/s; controlling the speed of oxygen injection to be 22-60 m/s;
the second step is that: the ore powder is heated to 1000-1400 ℃ in the preheating section of the furnace body by oxygen sprayed by the secondary combustion oxygen spray gun and the tertiary combustion oxygen spray gun, heat released by combustion of high-temperature furnace gas from the reduction section and physical heat of the high-temperature furnace gas, and the ore powder flows downwards to the reduction section after being melted and partially pyrolyzed/reduced; the mineral powder is rapidly reduced into ferrous oxide on the upper part of the reduction section and then drops into a metal molten pool; the ore powder flows downwards to a reduction section after being melted and partially pyrolyzed/reduced in a preheating section, and the pre-reduction degree of the ore powder is 15-20%;
the third step: spraying nozzleVolatile matters in the coal dust on the surface of the metal molten pool at the hearth section enter furnace gas, and the residual carbon particles are dissolved in the metal molten pool and undergo reduction reaction with ferrous oxide reduced in the mineral powder to generate CO and molten iron; the CO, furnace gas and coal volatile matter rise and drive high-temperature liquid metal and slag to form a Yongquan; CO, coal volatile matter and O introduced from oxygen lance at the upper part of reduction section 2 Carrying out combustion reaction, transferring the generated heat to liquid metal and slag drops brought by the phenomenon of Yongquan, transferring the heat to a metal molten pool through the falling back of the liquid drops, strongly stirring the metal molten pool and ensuring the reduction reaction;
the fourth step: molten iron smelted by the reduction reaction flows into a molten iron tank from a tap hole arranged at the lower part of the furnace body, and generated slag is discharged from a slag hole; the temperature of furnace gas in the reduction section is 1400-1580 ℃, the furnace gas preheats mineral powder when rising to the preheating section, and combustible materials are completely combusted; the flue gas generated by the reduction reaction is discharged through a smoke discharge section at the upper part of the furnace body, the temperature is 500-600 ℃, the flue gas is dedusted by a gravity deduster and then used for preheating and drying the powdered ore and the pulverized coal, the temperature of the flue gas is reduced to 100-150 ℃, the flue gas is dedusted by a cyclone and a cloth bag, one part of the purified flue gas is pressurized by a pressurizer to be used as a power medium for blowing the pulverized coal or the powdered ore, and the other part of the flue gas is directly discharged;
the furnace body of the matched pure oxygen two-section preheating reduction ironmaking furnace is provided with a smoke exhaust section, a preheating section, a reduction section and a hearth section; a plurality of cyclone mineral powder spray guns, a tertiary combustion oxygen spray gun and a secondary combustion oxygen spray gun are sequentially arranged on the upper section, the middle section and the lower section of the wall of the preheating section furnace and are all arranged at an angle tangent to a tangential circle in the furnace; an oxygen lance is arranged on the upper section of the reduction section, a coal lance is arranged on the lower section of the reduction section, and a nozzle of the oxygen lance and a nozzle of the coal lance point to a metal melting pool of the lower hearth section; a ceramic cup is arranged at the inner side of the furnace hearth section and used as a metal melting pool, and an iron outlet and a slag outlet are arranged at the side surface of the furnace hearth section;
the cyclone mineral powder spray gun, the tertiary combustion oxygen spray gun and the secondary combustion oxygen spray gun all enter the preheating section at an angle tangent to a tangential circle, the sprayed mineral powder and oxygen form a rotating fluid in the preheating section, the rotating fluid enhances the mixing of furnace gas, oxygen and mineral powder, so that all combustible materials are burned out, and the mineral powder is ensured to be intensively preheated in the process that the mineral powder falls to the reduction section in a manner of rotating along the furnace wall in the preheating section;
the total number of the cyclone mineral powder spray guns arranged in the preheating section is 1-8, the number of the third combustion oxygen spray guns is 1-4, and the number of the second combustion oxygen spray guns is 1-4; 2-9 coal guns are arranged at the reduction section, and 1-12 oxygen guns are arranged at the reduction section.
2. The pure oxygen two-stage preheating reduction ironmaking process according to claim 1, characterized in that: spraying the ore powder into a preheating section in the first step, wherein the temperature of furnace gas rises from a reduction section to the lower section of the preheating section, the furnace gas exchanges heat with the ore powder, oxygen for secondary combustion added from a secondary combustion oxygen spray gun is combusted with the furnace gas to increase the furnace temperature, and the heat for preheating the ore powder at the lower section of the preheating section is maintained; the middle section furnace gas in the preheating section is combusted with oxygen supplemented by the triple combustion oxygen lance, so as to ensure that combustible substances in the furnace gas are completely burnt out, improve the utilization rate of fuel and reduce CO 2 And (5) discharging.
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